How much chiller energy does raising the chilled water temperature by 1 degree save?
About 3% of chiller compressor power for each 1 degree C you raise the evaporator temperature, according to BEE's guide book on electrical utilities. Raising chilled water supply from 7 to 9 degrees C on a busy process chiller can cut its electricity by around 6%, provided the process still gets the cooling it needs.
Why a warmer setpoint saves power
A chiller's compressor works to lift heat from the evaporator pressure up to the condenser pressure. A warmer chilled water setpoint raises the evaporator temperature and pressure, so the lift is smaller and the compressor does less work for the same cooling. The 3% per degree figure is a rule of thumb for vapour compression chillers; your machine's part-load data sheet gives a closer number.
How far you can raise it
- Check the coldest user first: a jacketed reactor, a mould, a cold room or an air handler that must remove moisture.
- Air handlers that dehumidify need cold enough water to bring coil temperature below the dew point; raising the setpoint too far raises room humidity.
- Watch pump energy: warmer water carries less cooling per litre at the same temperature difference, so flow may rise and pumps work harder.
- Raise in steps of 0.5 to 1 degree, and log product quality and room conditions for a week at each step.
Turning the saving into kWh and CO2
- Find the chiller's annual kWh: from a submeter, or kW per TR times TR times running hours.
- Multiply by 3% per degree raised to get kWh saved.
- Multiply kWh saved by the grid factor, 0.710 kg CO2 per kWh, for location-based Scope 2.
- Compare the next year's chiller kWh at similar load and weather to confirm the saving.
Common mistakes
Applying 3% to the whole plant's electricity instead of the chiller alone; counting the saving at full load when the chiller runs mostly at part load; and raising the setpoint while users open their valves fully to compensate, which wipes out the gain.
Worked example: a 200 TR process chiller
- Running: 200 TR x 0.8 kW per TR = 160 kW, for 6,000 hours a year
- Annual use: 160 x 6,000 = 960,000 kWh
- Setpoint raised by 2 degrees C: about 3% x 2 = 6% saved
- kWh saved: 960,000 x 0.06 = 57,600 kWh
- CO2 saved: 57,600 x 0.710 = 40,896 kg, about 40.9 t CO2 a year
The 3% per degree is BEE's rule of thumb; confirm with before and after submeter readings.
What Senseible does here
Senseible reads kWh from your electricity bills and converts kWh to CO2 at the CEA factor of 0.710 kg CO2 per kWh, so a lower chiller load shows up in your monthly Scope 2 records.
Sources: BEE Guide Book 3, Energy Efficiency in Electrical Utilities, Chapter 4 Refrigeration and Air Conditioning (beeindia.gov.in), CEA CO2 Baseline Database, version 21.0
Last reviewed 2026-10-18.